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modelcontextprotocol--pytho…/examples/stories/extensions/server.py
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chore: import upstream snapshot with attribution
2026-07-13 12:10:27 +08:00

65 lines
1.9 KiB
Python

"""Package a vendor verb and a tool as a reusable, advertised extension (SEP-2133).
`custom_methods/` registers a verb on the lowlevel `Server` by hand; this story
bundles the same idea as an `Extension`: declared contributions, a settings entry
under `ServerCapabilities.extensions`, and a `require_client_extension` gate on
the vendor method.
"""
from collections.abc import Sequence
from typing import Any
import mcp_types as types
from pydantic import Field
from mcp.server.context import ServerRequestContext
from mcp.server.extension import Extension, MethodBinding, ToolBinding
from mcp.server.mcpserver import MCPServer, require_client_extension
from stories._hosting import run_server_from_args
EXTENSION_ID = "com.example/catalog"
class SearchParams(types.RequestParams):
"""Subclass `RequestParams` so `_meta` (and the 2026 envelope keys) parse uniformly."""
query: str
limit: int = Field(default=3, ge=1, le=25)
class SearchResult(types.Result):
items: list[str]
def suggest(prefix: str) -> str:
"""Suggest a catalog entry for a prefix."""
return f"{prefix}-suggestion"
async def search(ctx: ServerRequestContext[Any, Any], params: SearchParams) -> SearchResult:
require_client_extension(ctx, EXTENSION_ID)
return SearchResult(items=[f"{params.query}-{n}" for n in range(params.limit)])
class Catalog(Extension):
"""One identifier, three contributions: settings, a tool, a vendor method."""
identifier = EXTENSION_ID
def settings(self) -> dict[str, Any]:
return {"suggest": True}
def tools(self) -> Sequence[ToolBinding]:
return [ToolBinding(fn=suggest)]
def methods(self) -> Sequence[MethodBinding]:
return [MethodBinding("com.example/search", SearchParams, search)]
def build_server() -> MCPServer:
return MCPServer("extensions-example", extensions=[Catalog()])
if __name__ == "__main__":
run_server_from_args(build_server)